Frequently asked questions

BLEEDS is a research study collecting period blood, vaginal swabs and biopsies of the endometrium (a small tissue sample of the womb) to understand what’s really going on during a period — and why some people bleed heavily.

A biopsy is when a doctor or nurse takes a small piece of tissue from your body so it can be studied in the laboratory. The endometrium is the soft lining inside the womb that thickens every month and sheds during a period.

BLEEDS is run by the Wellcome Sanger Institute and led by Dr Roser Vento-Tormo. The project is funded by Wellcome Leap, under The Missed Vital Sign project.

Researchers will analyse period blood to understand which genes and cells are active, and what’s different for people with heavy periods.

Cells are the tiny building blocks of our bodies, with different types carrying out different jobs, such as fighting infections or forming the lining of the womb.

Genes are sections of DNA that provide instructions to help our cells work and our bodies grow and develop.

You can take part if you:

• Are aged 18 or over
• Have periods
• Have no history of reproductive cancers
• Live in England, Wales or Scotland
• (For biopsies only) Are not taking any hormonal treatments

No, participation is entirely voluntary, and you do not have to take part. You will be given a participant information sheet to keep, and if you choose to take part, you will be asked to sign a consent form. You are free to withdraw at any time, without giving a reason, and doing so will not affect your care or your legal rights.

You’ll receive a £30 voucher to reimburse you for your time donating period blood. If you choose to donate a biopsy, you’ll receive an additional £30 voucher for the extra time and travel involved. Every participant also receives a smart menstrual cup as part of the study kit, along with a subscription for the smart cup app.

Yes, you can take part in donating period blood for the study if you are using contraception. You can highlight any contraception or medication as part of completing the study health questionnaire within the study kit. Unfortunately, you cannot donate a biopsy if you are on hormonal contraception.

Completing the expression of interest form takes around 5 minutes, followed by a 30-minute consent appointment. Participation then involves donating one period sample and tracking the volume of your period over one cycle.

All menstrual cups come with instructions on how to use them.

You can wait until your next period to donate.

A biopsy is a small (about 1cm) tissue sample taken from the lining of your womb (endometrium). Donating a biopsy is entirely optional, and you can still take part in the BLEEDS study without this. If you do wish to donate a biopsy you would need to travel to Cambridge University Hospitals for this.

Your consent form will include a unique numeric identifier (Study ID). The health questionnaire, volume tracking form, and the samples you provide will only carry this Study ID — not your name or contact details.

No. This research is for scientific purposes only, and the Wellcome Sanger Institute aren’t able to provide clinical results or diagnoses. If you have concerns about your health, please speak to your GP or clinical team.

Your data can be shared with researchers from institutions around the world and the scientific community— see Keeping your data safe for more detail.

Yes, at any time and without giving a reason. Visit Withdraw from the study for exactly what this means for samples and data already collected.